I alt-f4'd cause I needed to quit the game quickly and next time I launched it I had no saves and when I exited galaxy synced the saveless game to the cloud overwriting everything.

Someone on reddit reported the same thing. It's sad to hear that this happens.
If you want, I can give you my save file. I've already finished the game and I have some skins unlocked, and I also started the hardcore mode, but you should be able to manually pick the level you were at and play the game.

I'm aware it's not the best solution and the devs should do something about it, but that's the only thing I can do.

If you want that save file, just ask :)